Considering the fuel requirement for such an occasion: Additional Fuel (called critical fuel at our outfit for such a case) should be carried on such a flight:
Critical Fuel is the fuel required at the most critical point along the routes, if a loss of one or two engines or loss of pressurisation occurs, to
- descent according to procedure and continue with LRC to a suitable AD and
- hold there for 15 min at 1.500' AAL
- and make an approach and landing
Critical fuel is of course only required, if the calculated minimum fuel is not sufficient for such an event.
Regards,
DBate